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  <title>Description of histc_sift</title>
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  <meta name="description" content="Creates a series of locally position dependent histograms of the values in I.">
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<h1>histc_sift
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<h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>Creates a series of locally position dependent histograms of the values in I.</strong></div>

<h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>function hs = histc_sift( I, edges, pargmask, weightmask ) </strong></div>

<h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre class="comment"> Creates a series of locally position dependent histograms of the values in I.

 Inspired by David Lowe's SIFT descriptor.  Takes I, divides it into a number of regions,
 and creates a histogram for each region. I is divided into approximately equally sized
 hyper-rectangular regions so that together these hyper-rectangles cover I.  The
 hyper-rectangles are actually 'soft', in that each region is actually defined by a
 gaussian mask, for details see mask_gaussians. pargmask, parameters to mask_gaussians,
 controls details about how the masks are created.  Optionally, each value in I may have
 associated weight given by weightmask, which should have the same exact dimensions as I. 

 INPUTS
   I           - M1xM2x...xMk numeric array
   edges       - either nbins+1 length vector of quantization bounds, or nbins
   pargmask    - cell of parameters to mask_gaussians
   weightmask  - [optional] size(I) numeric array of weights

 OUTPUTS
   hs          - histograms (array of size nbins x nmasks)

 EXAMPLE
   G = filter_gauss_nD([100 100],[],[],0);
   hs = histc_sift( G, 5, {2,.6,.1,0} ); figure(1); im(hs)

 DATESTAMP
   29-Sep-2005  2:00pm

 See also <a href="histc_1D.html" class="code" title="function h = histc_1D( I, edges, weightmask )">HISTC_1D</a>, <a href="mask_gaussians.html" class="code" title="function [masks,keeplocs] = mask_gaussians( siz, M, windowwidth, offset, show )">MASK_GAUSSIANS</a>, <a href="histc_sift_nD.html" class="code" title="function hs = histc_sift_nD( I, edges, pargmask, weightmask, multch )">HISTC_SIFT_ND</a></pre></div>

<!-- crossreference -->
<h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
This function calls:
<ul style="list-style-image:url(../matlabicon.gif)">
<li><a href="histc_sift_nD.html" class="code" title="function hs = histc_sift_nD( I, edges, pargmask, weightmask, multch )">histc_sift_nD</a>	Creates a series of locally position dependent histograms.</li></ul>
This function is called by:
<ul style="list-style-image:url(../matlabicon.gif)">
</ul>
<!-- crossreference -->



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